Remote Plasma Source Wall Passivation for Etch Stability
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Solution Overview
Problem
Remote plasma generators in PECVD processes face instability due to degradation of anodized aluminum coatings, leading to inconsistent wafer-to-wafer performance and excessive particulate generation, as the surface conditions change over time with plasma cleaning chemistries.
Innovation Solution
Exposing the interior wall surface of the remote plasma generator to a conditioning gas in an excited state, comprising oxygen-containing or nitrogen-containing gases, to passivate and stabilize the surface, thereby maintaining the substrate throughput and plasma performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If frequent chamber cleaning is performed to stabilize chamber conditions, then chamber stability is improved, but the anodized coating degrades at a much faster rate
Solution Approach 1:
The patent applies preliminary action by performing a specific conditioning treatment on the anodized aluminum coating before regular chamber cleaning cycles. This conditioning step modifies the surface properties of the coating in advance, making it more resistant to degradation during subsequent cleaning operations with chemistries like NF3. The conditioning process prepares the coating to withstand the cleaning environment, thereby extending its lifetime while maintaining chamber stability.
2Productivity
If the remote plasma generator operates continuously, then substrate throughput is improved, but the surface condition of the plasma block changes over time leading to inconsistent performance
Solution Approach 1:
The patent implements periodic action by introducing intermittent conditioning cycles during continuous substrate processing. Rather than operating the remote plasma generator continuously without interruption, the system periodically applies conditioning gas (such as oxygen or nitrogen) to the plasma block surface during operation. This periodic conditioning maintains consistent surface conditions on the plasma block, ensuring reliable plasma performance while allowing continuous substrate throughput through the use of multiple substrates or rapid cycling.
Solution Approach 2:
The patent applies self-service by enabling the remote plasma generator to condition its own plasma block surface during normal operation. The system uses a portion of the plasma power to generate excited species from the conditioning gas that directly treat the plasma block surface in situ. This self-conditioning mechanism maintains consistent surface properties without requiring external intervention or chamber shutdown, thereby maintaining both productivity and reliability.
3Strength
If the anodized aluminum coating is used to protect the aluminum interior walls, then protection from degradation is improved, but excessive particulate generation occurs due to coating failure
Solution Approach 1:
The patent applies parameter changes by modifying the surface properties of the anodized aluminum coating through exposure to conditioning gases (oxygen, nitrogen, or their mixtures). This conditioning process alters the chemical and physical parameters of the coating surface, such as surface energy, composition, and structure, making it more resistant to degradation. By changing these surface parameters in advance, the coating maintains its protective function longer, preventing the breakdown that would otherwise generate excessive particulates in the chamber.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method improves the lifetime of the anodized coating, reduces particulate generation, and ensures consistent plasma performance by stabilizing the surface conditions, resulting in improved deposition rates and uniformity.
Implementation Method 1
exposing an interior wall surface of a radical source to a conditioning gas that is in excited state to passivate the interior wall surface of the radical source
Implementation Method 2
a conditioning gas that is in excited state
Data Source
AI summary
Embodiments of the present disclosure generally relate to methods for conditioning an interior wall surface of a remote plasma generator. In one embodiment, a method for processing a substrate is provided. The method includes exposing an interior wall surface of a remote plasma source to a conditioning gas that is in excited state to passivate the interior wall surface of the remote plasma source, wherein the remote plasma source is coupled through a conduit to a processing chamber in which a substrate is disposed, and the conditioning gas comprises an oxygen-containing gas, a nitrogen-containing gas, or a combination thereof. The method has been observed to be able to improve dissociation/recombination rate and plasma coupling efficiency in the processing chamber, and therefore provides repeatable and stable plasma source performance from wafer to wafer.